This invention relates generally to fuel filters employed in connection with internal combustion engines. More particularly, the present invention relates to fuel filter systems having a replaceable cartridge for removing foreign particles and/or separating water from fuel of the fuel supply system of an internal combustion engine.
A number of conventional fuel filter systems perform the dual functions of removing particulate matter from the diesel fuel and separating water from the fuel. Conventionally, the fuel filter systems employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. In practice the filter cartridge requirements may vary depending upon such characteristics as the type and make of the internal combustion engine, the specific applications for which the engine is employed, the climate in which the combustion engine is operated and/or regional characteristics as to the quality of the fuel supply. The filter cartridges thus commonly vary as to their internal dimensions, their capacity, and the qualities of their filter media.
One of the problems which is frequently encountered in connection with replacement of the filter cartridge is ensuring that the replaced cartridge is compatible with the filtering requirements for the fuel system. Because numerous types and qualities of filter cartridges may dimensionally conform to the base of a given filter system, the replacement filter cartridge frequently does not comply with the specifications for the filter system, thereby jeopardizing the integrity of the fuel filtering system. Use of an incompatible filter cartridge can have very serious effects on the operation of the internal combustion engine, and may also be unnecessarily expensive when a less costly cartridge is fully suitable. Frequently, either the owner or the maintenance personnel servicing the internal combustion engine are totally unaware of the replacement filter cartridge specifications and requirements and unknowingly jeopardize the integrity of the filtering system by using non-conforming filter cartridges. There are also instances where inferior or improper replacement filter cartridges are intentionally installed without the knowledge of the owner or operator of the vehicle.
U.S. Pat. No. 5,035,797, which is assigned to the assignee of the present invention, discloses a key system for a filter system intended to address issues of filter cartridge compatibility. Fuel filter systems commonly comprise fuel inlet and outlets disposed in a base and a disposable filter cartridge which mounts to the base. Disposable filter cartridges constructed according to this invention have slots which are designed to mate with axial projections of the base. The projections obstruct the use of an incompatible cartridge by interfering with the mounting and sealing of the cartridge to the base. An alternative key system includes keys radially projecting from the communication end of a filter cartridge. The radial projections interfere with the reception of the filter cartridge in the base module. While these systems work well, they frequently require the manufacturer to design and manufacture a new base module for use with each differently keyed filter cartridge.
One aspect of filter system design and manufacture which tends to increase costs is the necessity of designing and manufacturing multiple variations of a given filter system to meet the headroom, flow, filtration and other requirements of particular applications. Filter base modules manufactured for a particular application frequently have an external configuration and/or internal key structures which make them useless for other applications. For example, U.S. patent application Ser. No. 09/785,785, filed Feb. 17, 2001 and which is assigned to the assignee of the present invention, discloses a Multi-Configurable Filter Base Module which illustrates an attempt to address this issue.
The multi-configurable filter base module uses a few standardized molded parts to create a wide variety of base module configurations. The multi-configurable filter base module is primarily directed to the external configuration of the base module, i.e., the configuration of the fuel inlet and outlet connectors and the mounting brackets on the outside of the filter base module. However, even a multi-configurable filter base module may have an internal structure keyed to accept only a particular filter cartridge and cannot be used for applications requiring a differently keyed filter cartridge.
Briefly stated, the invention in one preferred form comprises a key track system which may be incorporated into a filter base module and later efficiently configured to accept the key pattern of a filter cartridge appropriate to the end use.
Filter base modules, which are typically molded plastic or cast metal units, include a header portion which defines a receptacle for receiving the communication end of a filter cartridge and may include a lip structure for retaining a received cartridge. In an alternative retaining system, a retainer ring is threaded to the base module and engages a circumferential roll seam shoulder of the filter cartridge to retain the cartridge to the base module. When properly received in a base module, the communication end of a filter cartridge fills the header portion of the base module and receives the fuel inlet/outlet conduits projecting from the base module.
The present invention is directed to a key track fixture which may be molded or otherwise incorporated into a base module. One preferred form of the key track fixture is a flat metal ring including a plurality of angularly spaced perforations at least partially defining a series of parting lines for tabs which project radially outwardly from the interior edge of the ring. The key track fixture is mounted within the base module in such a manner that it defines the periphery of an entryway to the receptacle of the header portion. The configuration of this entryway may be altered by selective removal of tabs.
When the manufacturer wishes to create a filter system utilizing a filter cartridge having a particular communication end key configuration, the appropriate tabs are punched, or otherwise removed from the key track fixture retained in a base module. Thus, a generic base module may be efficiently configured to receive only a properly keyed filter cartridge. A key track fixture in accordance with the present invention, when combined with the use of interchangeable components, allows the manufacturer to create filter base modules having the desired external and internal configuration without having to design or manufacture new components.
In another embodiment of the invention, the key track fixture is in the form of a molded ring-like component which is ultrasonically welded in place. The inner edge of the fixture is defined by a plurality of angularly spaced keyway slots which are disposed at selected angular orientations which correspond to the keys at the communication end of the cartridge. The absence or presence of a slot at certain angular positions corresponds also to various characteristics of the filter cartridge such as water separating features, filter porosity and the customer model and other identification information for a given cartridge. The molded ring prior to installation may have one or more exterior notches so that the component may be suitably, angularly aligned with the rest of the header portion. In addition, a rim is provided to facilitate ultrasonic bonding of the molded component.
An object of the invention is to provide a new and improved key track system which provides for the efficient and cost effective production of generic filter base module components which may be efficiently configured to accept the key pattern of filter cartridges compatible with the requirements of the filter system.
Another object of the invention is to provide a new and improved key track system which allows the production of internally keyed filter base modules from a limited set of pre-fabricated components.